Coffee is a beverage with global and growing appeal, and there is an ever-increasing demand for high quality coffee. As is well known, coffee beans must be roasted prior to brewing. Roasting causes a complex series of chemical changes in the beans wherein sugars and/or other organic compounds are pyrolized, various volatiles are released and complex flavor elements are generated. The roasting process must be very carefully controlled, both in terms of time and temperature. Under-roasted coffee produces a thin, latex-flavored, bitter beverage, while over-roasted coffee is oily and burnt tasting. Prolonged roasting, even at an appropriate temperature, volatilizes many of the flavor elements and produces a beverage of little taste. Roasting is further complicated by the fact that some of the reactions occurring during the roasting are exothermic, and as a consequence, the beans can readily become overheated. It will therefore be appreciated that roasting is a very complicated process, typically carried out by trained personnel.
One standard roasting technique in the prior art comprises tumbling the coffee beans in a heated drum. While the hardware for the process is relatively simple, control is difficult, and it is very easy to scorch, and ruin the beans. Furthermore, smoke and oils generated in the process remain in contact with the beans and can confer a disagreeable taste. As a consequence, the industry is turning to the use of fluidized bed roasters. In systems of this type, the coffee beans are at least partially levitated by a stream of heated air, and the degree of roasting is controlled by controlling the temperature of the air and the duration of the heating cycle. While fluidized bed roasters eliminate problems of contamination by smoke and oils, care must still be taken to avoid scorching the beans. Toward this end, prior art fluidized bed roasting systems typically include some provision for quenching the beans after they are roasted, as for example by an introduction of a stream of cool air or by spraying the beans with water. U.S. Pat. No. 4,484,064 discloses a fluidized bed coffee roaster in which ambient air is used for cooling. A somewhat similar system is disclosed in U.S. Pat. No. 5,185,171. U.S. Pat. No. 3,964,175 discloses the use of a water spray to cool the beans.
It has been found that various flavor elements of roasted coffee dissipate quickly after the roasting process is complete. In an attempt to preserve the flavor of fresh roast coffee, the beans are vacuumed sealed, frozen, or enclosed in air tight containers for storage. Generally, because of the complexity of the coffee roasting process and the size and expense of the associated equipment it has not been practical to roast relatively small amounts of coffee at the point of purchase. However, it will be appreciated that in view of the superior flavor of fresh roasted coffee and the associated marketing value thereof, it would be desirable to have the coffee roasting apparatus which is relatively low in cost, simple to use and capable of quickly and precisely roasting a consumer sized amount of coffee beans.
As will be described in detail hereinbelow, the present invention provides a fluidized bed coffee roaster which is safe, fully automated in its operation and hence, operable by untrained personnel. The roaster may be charged with beans, set into operation, and left to run. The beans are automatically roasted to an appropriate degree, after which they are quickly cooled, thereby precluding the need to promptly remove them from the roasting chamber. These and other advantages of the present invention will be readily apparent from the drawings, discussion and description which follow.